Tuning pin drilling? followup

[Ron Nossaman]

>> ...I never found the need for high helix with the two bit method, 
>> though I have used them back in the single pass days. I don't like the 
>> way they burrow in.
> 
> I know what you mean, but that's not a problem with a very rigid set-up 
> outside the piano, and the great advantage is that far less heat is 
> produced.
> 
> JD

Nor is heat production with the low helix a problem with two 
pass drilling in the piano, with a considerably less than 
rigid setup.

I should qualify this. My 1/4" first pass is with a short 
flute bit about 10" long, which is plenty flexible. The second 
pass is with a 6.8mm jobbers length bit brazed into a 1/2" 
extension, so it's vastly more rigid than the first. The first 
pass produces plenty of heat, and likely a totally 
unacceptable uniformity in hole sizing. Since the 6.8mm second 
pass is only removing somewhere like 0.009" from the hole 
sides of the first pass, it reams and erases the 
inconsistencies of the first pass without generating 
problematic heat. As to uniform accuracy of the hole produced 
with minimal requirements of hardware and angst employed in 
the process, I haven't seen anything that comes close to it 
for me.

But as I said, the goal is the hole, regardless of the method 
employed.
Ron N